I. Field
The present disclosure relates generally to processes for conversion of a carbohydrate source to hexamethylenediamine and to intermediates useful for the production of hexamethylenediamine and other industrial chemicals. The present disclosure relates more specifically to chemocatalytic processes for the production of hexamtheylenediamine from a furfural substrate derived from a carbohydrate source, which substrate is converted to an intermediate comprising 1,6-hexanediol from which the hexamethylenediamine can be derived by chemocatalytic amination of the diol. The present invention is also directed to the production of 1,6-hexanediol from a furfural substrate in which at least a portion of the furfural substrate is converted to 1,2,6 hexanetriol, at least a portion of the hexanetriol is then converted to 1,6-hexanediol, and the 1,6 hexanediol is then converted to hexamethylenediamine by, for example, chemocatalytic amination of the diol. The present disclosure also relates to improved processes for the production of hexanediol from a furfural substrate.
II. Background
Hexamethylenediamine (HMDA) is a chemical intermediate primarily used in the production of nylon 6,6 via a condensation with adipic acid. HMDA is also used in the production of monomers for polyurethanes. Further, HMDA is used in the production of epoxy resins. Today, annual production of HMDA exceeds 3 billion pounds (avoir).
Crude oil is currently the source of most commodity and specialty organic chemicals. Many of these chemicals are employed in the manufacture of polymers and other materials. Desired chemicals include, for example, styrene, bisphenol A, terephthalic acid, adipic acid, caprolactam, hexamethylenediamine, adiponitrile, caprolactone, acrylic acid, acrylonitrile, 1,6-hexanediol, 1,3-propanediol, and others. Crude oil is first refined, typically by steam cracking, into hydrocarbon intermediates such as ethylene, propylene, butadiene, benzene, and cyclohexane. These hydrocarbon intermediates then typically undergo one or more catalytic reactions by various processes to produce these desired chemical(s).
HMDA is among those chemicals that continue to be produced commercially from oil via a multistep process. HMDA is typically produced from butadiene. Butadiene is typically produced from steam cracking of heavier feeds. The steam cracking of such feeds favors the production of butadiene, but also produces heavier olefins and aromatics. Thus, the butadiene resulting from the cracking step is typically extracted into a polar solvent from which it is then stripped by distillation. Butadiene is subjected to a hydrocyanation process in the presence of a nickel catalyst to produce adiponitrile. See, for example, U.S. Pat. No. 6,331,651. HMDA is then produced typically by the hydrogenation of adiponitrile in the presence of a solid catalyst. See, for example, U.S. Pat. No. 4,064,172 (which discloses a process for producing HMDA by hydrogenating adiponitrile in the presence of an iron oxide catalyst) and U.S. Pat. No. 5,151,543 (which discloses that HMDA can be prepared by hydrogenating adiponitrile in the presence of a Raney nickel type catalyst doped with at least one metal element selected from Groups 4, 5, and 6 of the periodic table of the elements and, more recently, WO-A-93/16034 and WO-A-96/18603 (each of which discloses Raney nickel catalyst based processes for the production of HMDA from adiponitrile) and US Patent Application No. 2003/0144552 (which discloses a process for producing HMDA from adiponitrile in the presence of a particularly conditioned Raney nickel catalyst).
Notably, each of the above-mentioned documents directed to the production of HMDA acknowledges the need for improvement in the efficiency, selectivity and commercial competitiveness of such process. In fact, the need for improved or alternative commercial processes for the production of HMDA is exacerbated by the evolution of the chemical industry toward the use of lighter feeds which, when subjected to cracking, produce lesser amounts of butadiene and ultimately will lead to increased costs of producing HMDA and increased price volatility.
For many years there has been an interest in using biorenewable materials as a feedstock to replace or supplement crude oil. See, for example, Klass, Biomass for Renewable Energy, Fuels, and Chemicals, Academic Press, 1998, which is incorporated herein by reference.
Recently, HMDA and other chemicals used in the production of, among others materials, polymers such as nylon have been identified as chemicals that may be producible from biorenewable resources, particularly carbohydrate containing materials from which glucose can be obtained and used as the feedstock to manufacture such chemicals. See, for example, US 2010/0317069, which discloses biological pathways purported to be useful to produce, among other chemicals, caprolactam and HMDA.
To date, there is no commercially viable process for the production of HMDA from carbohydrate containing feedstocks. Given the shift away from the production of conventional, oil-derived starting materials such as butadiene, notwithstanding the continuing growth in the markets for nylons and polyurethanes, among other materials, derived at least in part from HMDA or derivatives thereof and the benefits attributable to the use of renewable feedstocks in lieu of petroleum derived feedstocks, new, industrially scalable methods for the selective and commercially-meaningful production of chemicals from polyhydroxyl-containing biorenewable materials (e.g., glucose derived from starch, cellulose or sucrose) to important chemical intermediates such as HMDA is compelling.
1,6-hexanediol (HDO) has been prepared from, for example, adipic acid, caprolactone and hydroxycaproic acid. See, for example, U.S. Pat. No. 5,969,194. Recently, a process for the production of 1,6-hexanediol from furfural derived from glucose has been disclosed in WO2011/149339. The '339 application provides a general description of at least a two step catalytic process for the production of HDO from 5-hydroxymethylfurfural (HMF): hydrogenation of HMF to 2,5-bis(hydroxymethyl)tetrahydrofuran (BHMTHF, also referred to as 2,5-tetrahydrofuran-dimethanol or THFDM) followed by hydrogenation of BHMTHF to 1,2,6-hexanetriol (HTO); and then hydrogenation of 1,2,6-hexanetriol to 1,6-hexanediol. The processes disclosed in the '339 application require at least two different catalyst systems to produce 1,6-hexanediol from HMF. Furthermore, the reported yields of HDO from HMF ranging from 4% (directly to HDO) to 22% (using a 3 step process: HMF to THFDM, THFDM to HTO, and then HTO to HDO). The low yields reported in the '339 application clearly demonstrate the need for development of alternative, more efficient processes for the production of HDO.